Gav888

Hi,

Just a quick one, is there a reason why 2 x 20min threshold intervals are 20min in length, or would 2 x 30min or even 2 x 40min be better... providing you can do the 30min or 40min at threshold, or heart rate Zone 4 in Joe Friels cyclists training bible.

Im just wondering if 20min is the best time for these intervals as alot of people recommend 2 x 20min to be the best way to increase your power at threshold, is anything more or less not really worth it, a bit like vo2max intervals..... ive read that 4min is best, 5min is not hard enough to reach vo2max and anything less is too hard and you wont reach vo2max for long enough to make gains, is it the same as threshold 20min intervals or is it just a case of longer is better?

Thanks